3GPP 24.501 v20.0.0 — the document's own text
5.4.3.1 General
Taught in 6. Getting on the network, and getting a connection through it (CT1 — the group that writes what your phone says, in depth), 4. Inside TS 24.501, the document at the centre (CT1 — the group that writes what your phone says, overview).
The purpose of this procedure is to request a particular UE to provide specific identification parameters, e.g. the SUCI, the IMEI, the IMEISV, the EUI-64 or the MAC address. The SUCI is a privacy preserving identifier containing the concealed SUPI and the IMEI, the IMEISV, the EUI-64 and the MAC address are formats of PEI.